Basic electrophysiological properties of rat adrenal chromaffin cells and their sensitivity to muscarine were studied under voltage-clamp. Whole-cell patch-clamp recording of primary cultures of rat chromaffin cells reveals a prominent sodium current and one sustained component of calcium current. Outward currents are carried by three kinds of potassium currents: (1) a voltage-activated delayed-rectifier, (2) a voltage-dependent calcium-activated current and (3) a voltage-insensitive calcium-activated current. Muscarine (0.5 to 50 micromolar) suppresses spontaneous action potential firing and induces a slow outward current. This response persists in the presence of cobalt (5 millimolar). Voltage ramps during the response reveal that muscarine activates both voltage-dependent, TEA-sensitive and voltage-independent, curare-sensitive potassium currents in a manner consistent with a transient elevation of intracellular calcium. However, in some cells a marked transient suppression of the voltage-dependent component occurs coincident with the muscarine-induced increase in the voltage-independent potassium component. The suppression of the voltage-dependent component is washout sensitive in that it disappears over time, while the activation response is well maintained. / Source: Dissertation Abstracts International, Volume: 51-05, Section: B, page: 2230. / Major Professor: Christopher John Lingle. / Thesis (Ph.D.)--The Florida State University, 1990.

Source: Dissertation Abstracts International, Volume: 35-07, Section: A, page: 4237. / Thesis (Ph.D.)--The Florida State University, 1974.

The purpose of this study was to determine if an eight week exercise program would affect indices of bone integrity in postmenopausal women. Sixteen healthy, Caucasian, postmenopausal women, ages 51-74, participated in this study. All subjects were nonsmokers and had not engaged in regular physical activity for a minimum of three months. Eight subjects were assigned to the experimental group and participated in an eight week, three days per week, supervised exercise program and the remaining eight subjects remained inactive and served as the control group. All subjects maintained a constant self-selected diet which was analyzed for calcium, phosphorus, protein, fiber, and fat. Fitness evaluations based on one mile walk times and exercise heart rates were conducted prior to, and at the conclusion of, the eight week experimental period. Three indices of bone homeostasis, urinary calcium and hydroxyproline, and serum alkaline phosphatase, were used. Serum concentrations of calcium, ionized calcium, phosphorus, and creatinine, and urine concentrations of phosphorus and creatinine were also measured. Results showed the active experimental group had a significant (p $<$.01) improvement in predicted maximal oxygen consumption. The control group had a significant (p $<$.05) reduction in urine calcium and a nonsignificant reduction in urine hydroxyproline. The experimental group had nonsignificant increases in urine calcium and hydroxyproline. No significant changes were found for either group for serum alkaline phosphatase. The control group results (urine calcium decrease from pre to posttesting), when analyzed for other factors, showed a significant (p $<$.05) relationship to subjects taking medication for arthritis. Interference with intestinal calcium absorption from certain medications may have caused these unanticipated results. It was concluded that (1) / changes in calcium absorption need to be carefully monitored, (2) 8 weeks may be insufficient to produce significant changes in indices of bone formation (serum alkaline phosphatase), (3) the experimental group trends may indicate early changes in bone turnover leading to increases in bone formation. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0653. / Major Professor: Emily Haymes. / Thesis (Ph.D.)--The Florida State University, 1987.

Seven men, ages 19 to 33, served as subjects for the investigation of the thermophysiological effects of a triathlon performance in a warm humid environment. Each of the well-trained, acclimatized male triathletes performed a triathlon consisting of a 25 min swim, 75 min cycle ergometer ride and 40 min run. The cycle ride and run were performed in an environmental chamber at an intensity which produced 60-65% VO2 max in a neutral environment. Four environmental conditions were examined. The temperature and humidity for the neutral-dry condition (ND) was 21$\sp\circ$C/45%, the neutral-humid condition (NH) was 21$\sp\circ$C/83%, the warm-dry condition (WD) was 29$\sp\circ$C/45% and the warm-humid condition (WH) was 29$\sp\circ$C/45%. The environmental conditions were chosen to simulate environments typical of summer months in the southeastern and southwestern United States. A three-factor analysis of variance was used to analyze each dependent variable. Two of the main effects, temperature and humidity, were repeated over the third factor of time for each dependent variable. Significance was set at the 0.05 level. A Neuman-Keuls test was used to compare all significant pairs of means. Results showed significant interactions of heat with humidity resulting in higher heart rates, oxygen consumption, overall dehydrative weight loss and skin temperature in the WH condition. Ratings of perceived exertion for the WH triathlon demonstrated the same pattern when the results of the only Ironman Triathlete were not included. There was also an overall bronchodilation during triathlon performance in the WH environment. It is concluded that both skin and core temperature tend to rise with triathlon performance in the WH condition suggesting an escape from thermoregulatory control. It is important to note that although the instrumentation attests to quite a physiological / challenge with triathlon performance in the WH environment not all subjects will report the same perceived efforts. This could be a severe problem for medical supervision of triathlon events in such areas where conditions are usually warm and humid during the competition. / Source: Dissertation Abstracts International, Volume: 49-06, Section: A, page: 1401. / Major Professor: Emily M. Haymes. / Thesis (Ph.D.)--The Florida State University, 1988.

To determine if there are differences in substrate utilization of prepubertal girls and female adults during treadmill running, ten girls (mean age 9.1 $\pm$.6 years) and ten women (mean age 24.4 $\pm$ 5.2) underwent a 30 minute run at the same relative (70% VO$\sb2$ Max) (RI) and absolute (4mph/0% grade) (AI) intensity. Oxygen consumption (VO$\sb2$) and respiratory exchange ratio (RER) were monitored continuously during the exercise test by standard open circuit spirometry. Venous blood samples were obtained from an antecubital vein before and immediately after the termination of the exercise bout and were analyzed for lactate, glucose, FFA and glycerol concentrations. Differences between groups and over time were analyzed using ANOVA and ANCOVA design with repeated measures on the second factor. The Newman Keuls' post-hoc test was used to find significant differences between means (P $<$.05). / During exercise at the same RI, RER was significantly lower in the girls as compared to the women. In addition RER significantly decreased in the girls by the 20th and 25th minute of exercise at the same RI and AI respectively, while the change did not reach significance in the women. Lactate concentration increased significantly during the exercise tests. This change was significantly greater in the women (M = 1.36 mmol/L) than in the girls (M =.76 mmol/L) during exercise at the same RI, but greater in the girls (M =.603) than in the women (M =.356) during exercise at the same AI. FFA and glycerol concentrations were significantly higher after the exercise tests in both groups, while glucose concentration did not change significantly during tests. No inter-group differences were found in these energy substrates. / These results suggest that prepubertal girls rely more on fat utilization and less on carbohydrate metabolism than adults during treadmill running at the same relative intensity. In addition a significant shift in the relative contribution of CHO and fats to exercise occurs earlier in girls than adults during submaximal treadmill exercise at the same relative or absolute intensity. / Source: Dissertation Abstracts International, Volume: 52-04, Section: A, page: 1254. / Major Professor: Emily Haymes. / Thesis (Ph.D.)--The Florida State University, 1991.

Prolactin secretion is regulated by an endogenous rhythm of prolactin-releasing factors. This rhythm has a bimodal periodicity with distinct nocturnal and diurnal phases. Oxytocin, vasoactive intestinal peptide and serotonin play different roles in generating this endogenous stimulatory rhythm. We proposed that oxytocin is the neurohormone of this rhythm, whereas vasoactive intestinal peptide and serotonin act as neurotransmitters to release oxytocin. We investigated the role of this rhythm in female rats under varying physiological paradigms. Infusion of antagonists to oxytocin, vasoactive intestinal peptide and serotonin in ovariectomized, cervically stimulated rats were consistent with a role for the endogenous stimulatory rhythm in regulating mating-induced prolactin surges. Study of the ontogeny of this rhythm was also consistent with a role for this mechanism in driving mating-induced prolactin surges. / This endogenous rhythm is also important to prolactin secretion during lactation. Suckling-induced prolactin release was greater during the nocturnal and diurnal phases. Freely lactating rats secreted prolactin in a bimodal rhythm similar in periodicity to the endogenous rhythm. / Oxytocinergic neurons were analyzed for the presence of Fos protein as a marker of neuronal activity. A bimodal rhythm of oxytocinergic activity was present in the paraventricular nucleus. There was also a bimodal rhythm of oxytocin detected in the anterior pituitary coincident with the phases of the endogenous rhythm. / A diurnal rhythm of activity of vasoactive intestinal peptide neurons was detected coincident with the nocturnal phase of the endogenous rhythm in the paraventricular nucleus. / A diurnal rhythm of activity of serotonergic neurons was detected in the paraventricular nucleus coincident with the diurnal phase of the endogenous stimulatory rhythm. / These data clearly show that the endogenous stimulatory rhythm is an important regulator of prolactin secretion. Activity of oxytocin, vasoactive intestinal peptide and serotonin neurons are consistent with their proposed roles in generating the endogenous rhythm. The endogenous rhythm may be a common regulatory mechanism to prolactin secretion under varying physiological conditions. / Source: Dissertation Abstracts International, Volume: 53-03, Section: B, page: 1213. / Major Professor: Marc E. Freeman. / Thesis (Ph.D.)--The Florida State University, 1992.

Ten women, aged 18 to 34 years, served as subjects for this project to determine whether there was an acclimation effect due to repeated resting cold air (10(DEGREES)C) exposures. / The subjects were divided into two groups of five women each. One group, the acclimated (A) was exposed 10 times within two weeks, the first and the last exposures being the pre- and post-tests, respectively. The second group, the control (C) was exposed twice (pre- and post-tests) within 18 days. Measurements of rectal and skin temperatures, oxygen uptake, time to onset of shivering, and perceived cold were performed during all exposures. / A significant increase was seen in time to onset of shivering, and a significant decrease was seen in thermoregulatory heat production in the A group, and these changes were evident after about five exposures. A reduction in the feeling of discomfort was also seen with acclimation. However, no difference was seen in final body temperatures (rectal, mean skin, mean body and great toe) or in tissue insulation. / There was an acclimation effect from the repeated cold air exposures evidenced by the delayed onset of shivering, reduced cold induced thermogenesis, reduced heat loss, and increased feeling of well being by the acclimated subjects over the 10 exposures, and the adaptive responses appeared around the fifth and sixth exposures. / Source: Dissertation Abstracts International, Volume: 48-02, Section: A, page: 0331. / Thesis (Ph.D.)--The Florida State University, 1987.

Insulin dependent diabetes mellitus (IDDM) causes alterations in skeletal muscle at the biochemical and functional levels. Early signals initiating processes of muscle transformation are not known. One hypothesis suggests that alterations in energy state of a muscle may be causally related to altered gene expression. / The mechanistic basis of diabetes induced changes in energy supply and demand in skeletal muscle was evaluated. Experiments utilized an animal model of the disease, in which a condition similar to IDDM was induced in mice by injection of streptozotocin (STZ). The contents of phosphorous metabolites in quiescent fast and slow skeletal muscle were examined using phosphorous nuclear magnetic resonance spectroscopy and HPLC. STZ-injection decreased ATP, PCr, and the free energy of hydrolysis of ATP in slow twitch soleus (SOL) muscle, but not in the fast-twitch extensor digitorum longus (EDL). Maximal activities of selected enzymes, determined spectrophotometrically, also were decreased in SOL, but not in EDL. Alterations in contractile protein isoform composition occurred in both EDL and SOL, and the pattern of change was consistent with a fast to slow fiber-type transformation. In SOL, decreases in metabolite content preceded alterations in myosin expression at both protein and transcript levels. Alterations in the myosin isoform composition of the EDL occurred on a time scale consistent with those in SOL. / Myogenic factor transcript analysis demonstrates that expression of MRF4 is moderately increased after 5 weeks of STZ-diabetes in both EDL and SOL. These results suggest against involvement of fiber regeneration or processes of denervation mediating early changes in contractile proteins. / Decreases in phosphorous metabolite content are among the earliest changes in SOL from STZ-diabetic mice. Further, the temporal sequence of change is consistent with the hypothesis that intracellular energy state of muscle is mechanistically linked to alterations in gene expression. In fast twitch EDL it is suggested that exaggerated alterations in phosphorus metabolites occur during contraction. Thus, STZ-diabetes induced changes in energy state and contractile protein expression also may be causally related in the EDL. / Source: Dissertation Abstracts International, Volume: 56-03, Section: B, page: 1195. / Major Professor: Timothy S. Moerland. / Thesis (Ph.D.)--The Florida State University, 1995.

Intracellular diffusion of the energetically important phosphorous metabolites ATP and creatine phosphate (PCr) is crucial to the function of skeletal muscle. However, the effects of temperature on intracellular diffusion of these molecules have not been examined. In this study, diffusion coefficients (D) of ATP and PCr were determined in solutions of physiological ionic composition at 5$\sp\circ$C, 25$\sp\circ$C, and 40$\sp\circ$C; and D$\rm\sb{ATP}$ and D$\sb{\rm PCr}$ were determined in goldfish skeletal muscle at 5$\sp\circ$C and 25$\sp\circ$C. In vitro studies were performed using pulsed field gradient $\sp{31}$P nuclear magnetic resonance spectroscopy (PFG $\sp{31}$P NMR) and Plexiglas$\sp\circler$ diffusion cells. In vivo studies were performed using PFG $\sp{31}$P NMR. Results showed that changes in temperature had a significant effect on D$\rm\sb{ATP}\ and\ D\sb{PCr}$ in solution and in goldfish skeletal muscle. The observed Q$\sb{10}$'s for both D$\rm\sb{ATP}\ and\ D\sb{PCr}$ were 1.28 in vivo and 1.36 in vitro. This study showed that there were no significant effects of changes in pH or the concentration of Mg$\sp{++}$ on D$\rm\sb{ATP}$ in solution. Furthermore, there were no significant differences in D$\rm\sb{ATP}\ or\ D\sb{PCr}$ measured in red (oxidative) vs. white (glycolytic) muscle, or in muscle from goldfish acclimated to 25$\sp\circ$C vs. goldfish acclimated to 5$\sp\circ$C. / Measures of D$\rm\sb{ATP}\ and\ D\sb{PCr}$ in goldfish skeletal muscle were used to analyze the effects of temperature on the spatial distributions of ATP and PCr throughout activated goldfish muscle fibers. For these calculations, a mathematical reaction-diffusion model was developed incorporating the effects of temperature on diffusion coefficients, chemical reaction rates, and intracellular diffusion distances. Results indicated that diffusion of ATP and PCr was not limiting in red muscle at 5$\sp\circ$C or 25$\sp\circ$C, regardless of acclimation temperature. This appeared due primarily to the short spacing between mitochondria in red fibers. Availability of ATP may become considerably reduced at both 5$\sp\circ$C and 25$\sp\circ$C in white muscle, which has limited capacity for sustained ATP production. / Source: Dissertation Abstracts International, Volume: 56-03, Section: B, page: 1283. / Major Professor: Timothy S. Moerland. / Thesis (Ph.D.)--The Florida State University, 1995.

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